1. Field
A rechargeable lithium ion battery is disclosed.
2. Description of the Related Art
Recently, a lithium nickel composite oxide has been suggested as a positive active material capable of realizing a high potential and high capacity in a rechargeable lithium ion battery. However, when a rechargeable lithium ion battery using the lithium nickel composite oxide as a positive active material is stored at a high temperature in a full-charge state, there is a problem of generating a large amount of gas and deteriorating battery characteristics.
Although improving thermal stability of the lithium nickel composite oxide at a high temperature by adding cyclic carbonate having an unsaturated bond to an electrolyte solution has been attempted, that technology has a problem of increasing internal resistance of the rechargeable lithium ion battery and deteriorating its battery characteristics such as power and the like.